For the problem of multi-body contact and co-deformation in the stiffness analysis of angular contact thin-section ball bearings, an angular contact ball bearing 71718 is taken to investigate the axial stiffness of the thin-section bearing. Firstly, the reasonable finite element dimension is acquired based on the influence of the element dimension on the finite element analysis (FEA) results. Secondly, the finite element model of bearing 71718 is established to analyze the axial stiffness characteristics. Finally, the bearing axial stiffness test table was set up to test the axial stiffness of bearing 71718. The comparisons between test results and analysis results show that the Hertz analytical solutions has large calculation errors, the finite element results are close to real results, and the error is less than ten percent.